A conventinal safety syringe also invented by the present inventor of this application was patented on Apr. 27, 1993 of U.S. Pat. No. 5,205,826, which includes a hollow needle preliminarily held in a rigid blocking disk embedded in a rear disk socket perpendicularly formed in a flexible plug inserted in a front portion of the syringe for injection use having a needle head portion formed on a rear portion of the needle, and a plunger slidably held in the syringe for boosting a liquid medicine in the syringe to be injected into a patient through the hollow needle having a needle-head socket recessed in the plunger to be engageable with the needle-head socket for pushing the needle head portion of the needle frontwardly to drive the rigid blocking disk frontwardly to engage the blocking disk into a front disk socket which is normally inclinedly formed in the flexible plug and will be operatively perpendicularly biased in the plug when approximately exhausting the liquid in the syringe and finishing the injection, whereby upon a retraction of the plunger and the needle with the needle head portion received in and coupled to the plunger into the syringe to disengage the needle from the rigid disk, the flexible plug will restore the front socket and the rigid disk embedded in the front socket to be inclinedly positioned in the plug, thereby blocking an outward protruding of the needle retracted in the syringe for preventing its injury or infectious contamination to the surroundings.
However, such a conventional safety syringe may have the following drawbacks:
1. When the hollow needle 2 is held in the rigid blocking member 4 embedded in the flexible plug 13 in the syringe cylinder 11, the needle portion 21 with smooth surface may cause an automatic retraction of the needle 2 upon an injection of the needle tip end 211 into a patient's skin and upon an action by a counter force acted by the patient's skin to influence a normal injection operation.
2. The needle shank portion 22 is not bifurcated at its rear end portion to be lacking of elastic property for the hollow needle, thereby influencing or slowing down the coupling of the plunger 31 with the needle head portion 23 of the needle to cause an unsmooth needle injection and retraction operation for recovering a used needle into the syringe.
It is therefore expected to invent a needle which can be resiliently manipulated, held in a syringe for a smooth operation.